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main.cpp Example File
statemachine/factorial/main.cpp

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 #include <QtCore>
 #include <stdio.h>

 class Factorial : public QObject
 {
     Q_OBJECT
     Q_PROPERTY(int x READ x WRITE setX)
     Q_PROPERTY(int fac READ fac WRITE setFac)
 public:
     Factorial(QObject *parent = 0)
         : QObject(parent), m_x(-1), m_fac(1)
     {
     }

     int x() const
     {
         return m_x;
     }

     void setX(int x)
     {
         if (x == m_x)
             return;
         m_x = x;
         emit xChanged(x);
     }

     int fac() const
     {
         return m_fac;
     }

     void setFac(int fac)
     {
         m_fac = fac;
     }

 Q_SIGNALS:
     void xChanged(int value);

 private:
     int m_x;
     int m_fac;
 };

 class FactorialLoopTransition : public QSignalTransition
 {
 public:
     FactorialLoopTransition(Factorial *fact)
         : QSignalTransition(fact, SIGNAL(xChanged(int))), m_fact(fact)
     {}

     virtual bool eventTest(QEvent *e)
     {
         if (!QSignalTransition::eventTest(e))
             return false;
         QStateMachine::SignalEvent *se = static_cast<QStateMachine::SignalEvent*>(e);
         return se->arguments().at(0).toInt() > 1;
     }

     virtual void onTransition(QEvent *e)
     {
         QStateMachine::SignalEvent *se = static_cast<QStateMachine::SignalEvent*>(e);
         int x = se->arguments().at(0).toInt();
         int fac = m_fact->property("fac").toInt();
         m_fact->setProperty("fac",  x * fac);
         m_fact->setProperty("x",  x - 1);
     }

 private:
     Factorial *m_fact;
 };

 class FactorialDoneTransition : public QSignalTransition
 {
 public:
     FactorialDoneTransition(Factorial *fact)
         : QSignalTransition(fact, SIGNAL(xChanged(int))), m_fact(fact)
     {}

     virtual bool eventTest(QEvent *e)
     {
         if (!QSignalTransition::eventTest(e))
             return false;
         QStateMachine::SignalEvent *se = static_cast<QStateMachine::SignalEvent*>(e);
         return se->arguments().at(0).toInt() <= 1;
     }

     virtual void onTransition(QEvent *)
     {
         fprintf(stdout, "%d\n", m_fact->property("fac").toInt());
     }

 private:
     Factorial *m_fact;
 };

 int main(int argc, char **argv)
 {
     QCoreApplication app(argc, argv);
     Factorial factorial;
     QStateMachine machine;

     QState *compute = new QState(&machine);
     compute->assignProperty(&factorial, "fac", 1);
     compute->assignProperty(&factorial, "x", 6);
     compute->addTransition(new FactorialLoopTransition(&factorial));

     QFinalState *done = new QFinalState(&machine);
     FactorialDoneTransition *doneTransition = new FactorialDoneTransition(&factorial);
     doneTransition->setTargetState(done);
     compute->addTransition(doneTransition);

     machine.setInitialState(compute);
     QObject::connect(&machine, SIGNAL(finished()), &app, SLOT(quit()));
     machine.start();

     return app.exec();
 }

 #include "main.moc"